Disclosed are intermediate transfer members, and more specifically, intermediate transfer members that can be selected for receiving developed images followed by transferring these images in an electrostatographic, for example xerographic, including digital, image on image, and the like, machines or apparatuses and printers, and yet more specifically, printers that generate images of various colors. In embodiments, there are disclosed intermediate transfer members comprised of an optional supporting substrate such as a polyimide first layer, and a UV (ultraviolet light) curable or UV cured second layer comprised of a self conductive dendritic polyester polyol acrylate with for example, a resistivity of from about 108 to about 1013 ohm/sq and from about 108 to 1010 ohm/sq as measured by a Hiresta resistivity meter, (the language from about to about includes all values in between the values disclosed) and a photoinitiator; and which second layer may optionally include therein vinyl monomers, and acrylates, like for example, a fluorinated acrylate that primarily functions to assist in providing a low energy surface layer, permitting excellent toner transfer and acceptable toner and debris cleaning efficiencies in xerographic systems, and where the polyimide substrate layer when present further optionally includes a conductive component.
A number of advantages are associated with the intermediate transfer members of the present disclosure in embodiments thereof, such as acceptable mechanical characteristics, robustness, consistent, and excellent surface resistivities, excellent image transfer (toner transfer and toner cleaning), as compared to a number of known intermediate transfer members with a polyimide base layer and free of dendritic polyester polyol acrylates; acceptable adhesion properties, especially when there is included in the plural layered intermediate transfer member an adhesive layer; excellent maintained conductivity or resistivity for extended time periods; dimensional stability; ITB (intermediate transfer belt) humidity insensitivity for extended time periods; excellent dispersability in a polymeric solution; low and acceptable surface friction characteristics; and minimum or substantially no peeling or separation of the layers.
More specifically, the UV curing of the intermediate transfer members illustrated herein provides in embodiments almost zero VOC volatiles; preparation efficiencies, for example cured within seconds; excellent physical properties such as stain, abrasion, and solvent resistance together with superior toughness, and excellent gloss characteristics.
Also, the intermediate transfer members of the present disclosure are UV curable due primarily to the transparency characteristics of the dentritic polyester polyol acrylate containing layer and in embodiments which second layer possess for example, a surface resistivity of from about 108 to about 1013 ohm/sq.
Accordingly, in embodiments of the present disclosure, the intermediate transfer members are UV curable which allows the UV light to penetrate across the dentritic polyester polyol acrylate containing second layer for a complete, almost 100 percent, cure. In comparison, intermediate transfer members that include about 5 weight percent of carbon black in a second layer in contact with a first supporting substrate layer, possesses a resistivity of for example, over 1014 ohm/sq. Also, a carbon black containing second layer substantially prevents UV light from penetrating deep into the layer, thus a preselected cure or a complete cure is difficult to obtain.
In a typical electrostatographic reproducing apparatus, such as xerographic copiers, printers, multifunctional machines, and the like a light image of an original to be copied is recorded in the form of an electrostatic latent image upon a photosensitive member or a photoconductor, and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles and colorant. Generally, the electrostatic latent image is developed by contacting it with a developer mixture comprised of carrier granules having toner particles adhering triboelectrically thereto, or a liquid developer material, which may include a liquid carrier having toner particles dispersed therein. The developer mixture is advanced into contact with the electrostatic latent image, and the toner particles are deposited thereon in image configuration. Subsequently, the developed image is transferred to a document, such as paper and fixed or fused by for example heat and pressure. It is advantageous in some instances to transfer the developed image to a intermediate transfer web, belt or component, and subsequently, transfer with a high, for example about 90 to about 100, transfer efficiency the developed image from the intermediate transfer member to a substrate, like paper, cardboard, transparencies, and the like.
It has been reported in several U.S. patents that intermediate transfer members enable acceptable registration of the final color toner image in color systems using synchronous development of one or more component colors, and using one or more transfer stations; and all for an increase the number of substrates that can be selected. However, a disadvantage of using an intermediate transfer member is that a plurality of developed toner transfer operations is utilized thus causing charge exchange between the toner particles and the transfer member, which ultimately can cause less than complete toner transfer, resulting in low resolution images on the image receiving substrate, like paper, and image deterioration. When the image is in color, the image can additionally suffer from color shifting and color deterioration.
Attempts at controlling the resistivity of intermediate transfer members, such as intermediate transfer belts (ITB) by, for example, adding conductive fillers, such as ionic additives and/or carbon black to the outer or top layer, are disclosed in U.S. Pat. No. 6,397,034 which patent describes for example, the use of fluorinated carbon fillers in a polyimide intermediate transfer member layer. However, there can be problems associated with the use of a filler particles in that undissolved particles frequently bloom or migrate to the surface of the fluorinated carbon filler and cause imperfections on the surface, thereby causing nonuniform resistivity, which in turn causes poor antistatic properties and poor mechanical strength characteristics. Also, ionic additives on the ITB surface may interfere with toner release. Furthermore, bubbles may appear in or on the surface top layer, some of which can only be seen with the aid of a microscope, and other bubbles of which are large enough to be observed with the naked eye resulting in poor or nonuniform electrical properties, and poor mechanical properties.
In addition, the ionic additives themselves are sensitive to changes in temperature, humidity, and operating time. These sensitivities often limit the resistivity range. For example, the resistivity usually decreases by up to two orders of magnitude or more as the humidity increases from about 20 to about 80 percent relative humidity, which limits the operational latitude.
Moreover, ion transfer may also occur in the U.S. Pat. No. 6,397,034 systems. The transfer of ions leads to charge exchanges and insufficient transfers, which in turn causes low image resolution and image deterioration, thereby adversely affecting the copy quality.
Therefore, it is desired to provide an intermediate transfer member with a number of the advantages illustrated herein, inclusive of enabling excellent mechanical, and humidity insensitivity characteristics; permitting high copy quality where for example, developed xerographic images with minimal resolution issues can be obtained. It is also desired to provide a weldable intermediate transfer belt that may not, but could have puzzle cut seams, and instead has a weldable seam, thereby providing a belt that can be manufactured without labor intensive steps, such as manually piecing together the puzzle cut seam with fingers, and without the lengthy high temperature and high humidity conditioning steps. Also, it is desired to generate by environmental acceptable standards intermediate transfer members, achievable in embodiments of the present disclosure, where these intermediate transfer members can be obtained in the absence of solution casting methods and where solvent evaporation is not present.